Roller-type enlarging or reaming bit



Feb. 23, 1965 K,vT RosKEN ETAL 3,170,524

- ROLLER-TYPE ENLARGING O R REAMING BIT File r 1 6.- 1960 y 2Sheets-Sheet 1 A I:Aryan/Tops "ywbfA-u Af," dem @MJ Feb- 23, 1965 K.'rRosKr-:N Erm. 3,170,524

ROLLER-TYPE ENLARGING 0R REAMING BIT Filed April 6, 1960 2 Sheets-sheet2 Fig.3

g1 l) /NvE/vrons c AUnited States Patent O 4 Claims. (l. 11s-s3) Thisinvention relates to roller-type enlarging or reaming bits having yaplurality of freely rotatable cutting rollers mounted on armsdistributed in the form of a star on a base body, as used in so-calledpulling or drawing dri-lling for enlarging or reaming out preparatorydrillholes through which the drilling rod is then passed.

In the known types of such tools the cutting rollers, which sweep overthe annular shoulder between the periphery of the enlarged drillhole andthe preparatory drillhole during the rotation of the drilling rod, areequipped with a plurality of cutting ribs or serrations distributed inthe axial direction over their periphery. These cutting ribs4 are forcedinto the solid rock under the pulling action exerted on the drilling rodand break Iaway the rock to be broken down peripherally of thedrillhole. In view of the only linear contact between the cutting ribsand the base of the drillhole the cutting ribs, which follow veryclosely one to the other, are subjected to extremely heavy mechanicalstresses and Wear out very rapidly even if, accepting thecorrespondingly higher cost, they are made of specially wear-resistantmaterial.

Furthermore, the pulling forces which can be exerted by the drilling rodon tools equipped with such cutting rollers are limited. On a givenmaximum pulling force being exceeded, this pulling force depending inany individual case on the hardness of the rock, the cutting rollerstend to jam temporarily and then to continue to turn spasmodicallythrough a larger peripheral distance, which results in correspondinglyintermittent stresses on the drilling rod.

The present invention provides a roller-type enlarging bit whichobviates these drawbacks and is achieved by a structure which typicallycomprises a drill stem to be pulled through a pilot hole, at least twopins radially extending from the trailing end of the drill stem, theaxis of each of the pins being inclined toward the direction of travel,and a cutter rotatably mounted on each of the pins, each of the cuttersbeing provided with a plurality of spaced circumferential rows ofWedge-shaped cutting ribs.

By this arrangement of the cutting ribs, the cutting rollers, under theinfluence of the pulling force exerted by the drilling stem, effectivelybreak away the rock adjacent the ribs toward the axis of the pilot holeduringthe circular paths ascribed by the rollers.

The pressure component acting in the direction of the preparatorydrillhole is obtained by wedge-shaped proling of the cutting ribs insuch manner that the inclination of the wedge-shape to a plane normal tothe axis of the cutting roller is greater on the side directed towardsthe preparatory drillhole than on the side facing away therefrom.

The action of the cutting rollers constructed in the manner set forth inits essentials above is also assisted in that the cutting ribs of thesuccessive rollers arranged at equiangular separation around theperiphery of the drilling rod, for instance the cutting ribs of threesuch rollers, are offset with respect to one another, so that thesucceeding roller in each case becomes operative in the area between thegrooves formed by the cutting ribs of the preceding roller.

3,170,524 Patented Feb. 23, 1965 ICC By designing the cutting rollersaccording to the invention, completely smooth running of the cuttingrollers is obtained and the danger of any jamming of the rollers iseliminated. Due to these facts it becomes possible to operate withgreater pulling forces on the drilling Yrod and thus to achieve a higherrate of advance in the drilling operation, intermittent stressing of thedrilling rod being entirely obviated.

The invention also includes a cutting roller for a roller-type enlargingbit, said cutting roller according to the invention having cutting ribsarranged so that they extend coaxially to one another in the peripheraldirection of the roller and lat axial intervals from one another. Y

The details and further features of the invention will appear from thefollowing description of an embodiment of the new roller-type enlargingbit given with reference to the accompanying drawings, which vare merelydiagrammatic.

In the drawings:

FIGURE l illustrates in side elevation the general arrangement of thetool inserted in a drillhole which is to be enlarged withparts removedto more clearly illustrate the structure, j

FIGURE 2 is a plan view of the general arrangement illustrated in FIG. lshowing the bit in its operative position, as in FIG. 1,'inserted in adrill hole bottom of the drillhole, v

FIGURE 3 is an enlarged fragmentary elevational view of the cutterillustrated in FIGS. l and 2, and

FIGURE 4 is a plan view of a tool similar to that illustrated in FIGURE2 and specifically illustrating a modivtied form of the arrangement ofthe cutting ribs on the 'associated cutters.

In FIGURE l, the reference letter a designates the drilling rod of thenew drilling tool, which carries the base body b of three-armed typeaccording to the embodiment, on the arms c of which, that is theterminal spigots thereof, the cutting rollers d are exchangeably mountedin the usual manner.

In FIGURE 2 there can be seen the effect of the offsetting with respectto one another of the series of cutting ribs of the several cuttingrollers following one another in the peripheral direction.

The unique design of the rollers which forms the subject-matter of theinvention is apparent in particular from FIGURE 3. In this figure therecan be seen the cutting ribs e-there are ve such ribs according to theembodiment-arranged in the direction of the periphery of the roller bodyat suitable axial intervals from one another. As shown at f, theeffective edges of these cutting ribs are so profiled in tiltedgable-roof or wedge-like fashion that the inclination of the side i ofthe wedge-shape f-acing the preparatory drillhole with respect -to aplane normal to the axis of the roller `is greater than Ithat of theside f remote from the drillhole, which latter side of the gable roof,according to the embodiment, extends parallel to the axis of thedrillhole. Of course, the cutting ribs are toothed, as indicated inpurely diagrammatic manner in FIGURE 3 by showing a few teeth. It willbe appreciated that the cutting ribs e have a wedge-like asymmetricalprofile such that the inclination of the faces f' of the ribs e whichface toward the body portion of the drill stem with respect to a planenormal to the axis of the roller d is greater than the inclination ofthe face f directed toward the circumference of the bore hole.

In FIGURE 3, arrows g', g" indicate the .resulting force components,namely the breaking-up component g acting in the direction of the axisof the drillhole and the forcing-away component g" acting towards thepre-v paratory drillhole;

The circumferences of the cutting ribs, which increase in the directionof the periphery of the enlarged drillhole, are determined by theconventional inclined position of the annular bottom of the drillhole.

In addition to the advantages as regards function already describedabove, the roller-type bit according to` the invention alsohas thefurther advantage that manufacture, including the application of thewearresistant FIGURE 4 illustrates a modified form' of the invern tionwherein the cutting ribs on one of the cutting rollers is oset in anaxial direction with respect tothe cutting ribs of the succeedingcutting roller. More specically,

the cutting roller d is provided withgcutting ribs e which are olsetwith respect to the cutting ribs e on the cutting the axes of said pinmembers being inclined yrelatively to the longitudinal axis of saiddrill stern,` and a cutting Vroller mounted to rotate about an axis oneach of said pin members, each of said cutting Yrollers having aplurality of circumferentially disposed cutting ribs of Wedge-shapedcross sectional prole', the inclination of the portion'of thewedge-shaped cross section of said cutting ribs withV respect to a planenorma-l to theaxisofsaid cutting roller being greater on the side ofsaid cutting rib facing towards '10 lhard surfacing h indicated inFIGURES, is simpler and accordingly cheaper. v

roller d; while the cutting ribs e on the cutting roller d" are-odsetwith respect to thevcutting ribs e on the cutting roller d. y

:The conventional practice utilized in the assembly and .i use ofroller-type enlarging or reaming bits `is described l in detail in theGerman mining journal entitledfGlckauf, April 23', 1955, page 446.

Of course', the invention irslnot` limited to the form of embodimentdescribed above'in detailand illustrated in the drawings, numerousmodifications being possible in` said lbody portion than on thesidefacing away therefrom. A

2. A rolleri type enlarging bit as claimed in claim l wherein thecutting ribs ofthe one ofk said cutters is oilset with respect to thecutting ribsrof the succeeding one of said cutters. v 3. A `roller typeenlarging bit as claimed in claim 2 wherein the wedge-shaped'cross-,section of said. cutting ribs is unsymmetrical. Y

4. A roller type enlarging bit comprising a drill stem to be pulledthrough a pilot hole, said drill stern having a longitudinal axis, atleast two pins1radially extendingl from the trailing end of said drillstem,{the axis of eachl of said pins being inclined away fromrthedirectionof longitudinal travel of said drill stem, and a cutterrotatably mounted on each'of said pins, each of said cutters be-` ingYprovided with la plurality of spaced icircumferential rows ofwedge-shaped cutting ribs, said drill stem prof viding the sole meansfor transmitting rotary motion to stem adapted to extend in a pilotdrill hole, pin members 35 extending from saidbody portion in astar-like fashion,

saidl pinsv and rotably mounted cutters and for maintaining pressure onsaid cutters in the direction of cutting. y

References Cited in the le of this patentl UNITED STATES 'PATENTS1,661,715V cansan s Mar. 6, 192s" 2,746,719 sengman May 22, 1956`2,790,625

Dean Apr. 30, 1957

1. A ROLLER-TYPE ENLARGING BIT COMPRISING A DRILL STEM HAVING ALONGITUDINAL AXIS, A BODY PORTION MOUNTED ON ONE END OF SAID DRILL STEM,THE OTHER END OF SAID DRILL STEM ADAPTED TO EXTEND IN A PILOT DRILLHOLE, PIN MEMBERS EXTENDING FROM SAID BODY PORTION IN A STAR-LIKEFASHION, THE AXES OF SAID PIN MEMBERS BEING INCLINED RELATIVELY TO THELONGITUDINAL AXIS OF SAID DRILL STEM, AND A CUTTING ROLLER MOUNTED TOROTATE ABOUT AN AXIS ON EACH OF SAID PIN MEMBERS, EACH OF SAID CUTTINGROLLERS HAVING A PLURALITY OF CIRCUMFERENTIALLY DISPOSED CUTTING RIBS OFWEDGE-SHAPED CROS SECTIONAL PROFILE, THE INCLINATION OF THE PORTION OFTHE WEDGE-SHAPED CROSS SECTION OF SAID CUTTING RIBS WITH RESPECT TO APLANE NORMAL TO THE AXIS OF SAID CUTTING ROLLER BEING GREATER ON THESIDE OF SAID CUTTING RIB FACING TOWARD SAID BODY PORTION THAN ON THESIDE FACING AWAY THEREFROM.